Bone conduction hearing-aid device



Jam.. l0, i3.,

E. c. NrcrioLlDl-:s

BONE CONDUCTION` HEARING-AID DEVICE Filed July l, 1936 2 Sheets-Sheet lINVENTOR EQNICHGLIDES BY SM'JFAMA ATTORNEY Jan. 10, 1939.

lE. C. NICHOLIDES BGNE CONDUCTON HEAIlNG-AID DEVICE Filed July l, 1956 2Sheets-Sheet 2 *i OO @915512. f O

ATTORNEY Patented Jan. 10, 1939 UNITED STATES PATENT ori-ICE signor toSonotone Corporation, New York, N. Y., a corporation of New YorkApplication July 1.1, 1936, Serial No. 88,322

4 claims. (cl. 11s- 1075 This invention relates to bone conductionhearing-aid devices and has among its objects a flat small boneconduction receiver for inconspicuous wear in contact with hearinginducing bone structure of a deafened person designed to operate withhigh efficiency in impartingto the bone structure of the user thehearing inducing vibratory energy required for inducingsatisfactoryhearing-` The objects of the invention will be bestunderstood from the following description of exemplifications thereof,reference being had to the accompanying drawings, wherein Fig. 1 is avertical cross sectional view oi' a bone` conduction receiver oftheinvention with the head-band support;

Fig. 2 is an elevational view of the receiver of Fig. 1 partially incross section. alongline 2--2 of Fig. 1; c

Fig. 3 is a horizontal sectional receiver along line 3-3 of Fig. 1;

Fig. 4 is a top view of the inner side of the base of the receiver ofFig. f1 with the armature mounted in place;

Fig. 4a is a yperspective view of a modified head` view oi' the e Ibandswivel support; l

Fig. 5 is a perspective view of the core assembly of the receiver ofFig. 1; i i e Fig. 6 is a diagram illustrating a hearing-aide. devicewith a bone conduction receiver of the invention as used by a deafenedperson; l

Fig. 7 is a view similar to Fig. 1 of a bone con. duction receiveradapted for couplingto` hearinginducing vertebrae of a deafened person;j f Fig. 8 is an elevationalview of the receiver with Fig. 9 is ahorizontal sectional view of the receiver along line9-9 of Fig. 7; l

Fig. 10 is a side elevation of the receiver of Fig. 7;

Fig. 11 is a perspectiveview of the core assembly of Fig. 7; e i

Fig. 12 is a view of the bone conduction receiver of Fig. '7 and itscoupling support; e

Fig. 13 is a view similar to Fig. 1 of a bone conduction receiverembodying a modiiied form of the invention;

Fig. 14 is a plan view of the receiver of Fig. 7 with the cover removed;and e.

Fig. 15 is a horizontal sectional View oi the receiver along line |5|5of Fig. 13.

It has been long known that 'most of the deafened are anxious to concealtheir impairment and that a practical hearing aid for a dea'fened personmust not only be able to make the deafened hear sound substantially:like a normal person, but that i floating condition a driving atmagnetic core i the hearing-aid must be suitable for concealed wear bythe user.

In accordance with the invention a small eiiicient bone conductionreceiver suitable for incon spicuous wear in contact withhearing-inducing bone structure of a deafened person is made with a flatfloating magnetic vibrating structure of substantial mass formed by twomagnetic bars of substantial mass and magnetic pole pieces joining theopposite ends of the bars into a nat rigid structure which`substantially fills the interior of the receiver casing and connes theactuating winding and pole members of the vibrating struc-` ture withinthe space between the magnet bars, thus limiting the over-all height ofthe receiver to a minimum. l.

In Figs. 1 to 5 is illustrated one form of such boneconduction receiverintended for wear in contact with the mastoid bone behind theear of l ithe user: It comprises a flat small casing 2U formedoi a base `2| and adetachable cover 22 enclosing an electromagnetic vibrating structureconsisting ofa driven armature core member 23 which is clamped to thebase 2| and supports in a structure 24 of substantial mass which llssubstantially the entire interior space of the casing.

The `floating. magnetic core `structure `24 is formed `of twolongitudinal slightly curved permanent magnetic bars 30,`the oppositeends of which 30 are attachedby screws 3| to cross pieces 33 of twoT-shaped core members` 34` which have angularly l bent longitudinallyextending central pole projections 35 terminating in inwardly projectingpole pieces 36 which face the armature 23.

The armature 23 is united as by soldering with a diaphragm strip 3l,which has its ends rmly clamped to` the core cross pieces 33 bynon-magnetic screws 38, and non-magnetic spacers 39, of a thicknessequal to the thickness of the armature 23 to separate the ends of thediaphragm 31 from the cross piece 33, and prevent a magnetic shortcircuit between the core pieces of opposite polarity. On the pole pieces36 are mounted actuating windings in the form of coils 40, and the coilsas 45 well as the pole pieces are confined within` the space betweenthemagnet bars 30.

Eilicient operation of the electromagnetic v1'- brating structure,formed of the armature 23 and the large mass of the iloating magneticcore 24, is secured by fixing the gaps between the pole pieces 36 andthe armature 23 at a very small distance the order of about one-half ofa thousandth of an inch atwhich the amplitudes of the core vibra-` tionsacross ,the gap is of the order of the gap lengths while eliminatingfreezing.

Accurate manufacture of bone conduction receivers, with the small gapdistance of the order of one-half of a thousandth of an inch essentialfor efficient operation is made possible by providing each inward polecore projection 35 with a set screw 42 having shoulder portions 43engaging the opposite surfaces of the core cross piece 33 so that byturning the set screw 42 the pole piece core is deformed and withdrawnfrom its contact with the armature and retained in a fixed position inwhich a small effective magnetic gap of a fraction of a thousandth of aninch is maintained between the pole faces of the pole pieces 36 and thearmature 23 during the oper-- ation of the receiver.

In order to permit accurate fixing of the effective magnetic gaps in themanufacture of such receivers, the surface of the assembled floating.core structure 24 facing the armature is ground flat and the pole facesof the pole pieces 36 are made level "with the aligned surfaces of thecross pieces 33 so that when the armature 23 is clamped to the corestructure 24, the inward endsof the pole pieces 36 make contact with thearmature.

The vibratory magnetic structure is then given the fixed dimensionsrequired for operation with the optimum effective magnetic gap length ofa fraction of a thousandth of an inch by turning the set screws 42 inthe screw holes 42' of the pole cores 35 till the pole pieces 36 aremoved away from contact with the armature and the effective magnetic gapis fixed at the desired small length at which the accelerating magneticforces acting through the gap impart to the core members a vibratorymotion across the gap of the order of the gap length without danger offreezing or fringing between the pole faces` The set screws 42 have asmall pitch so that a substantial angular turn of the set screw producesonly a small motion of the pole piece, permitting accurate setting ofthe optimum fixed gap distance upon which the efficiency of the receiverdepends.

The assembled vibrator unit formed of the floating core structure 24 andthe armature 23 is mounted as a unit on the base 2| by two screws 46which clamp the center portion of the armature to a metallic anchorplate 41 rigidly imbedded in the molded base 2|. Sound frequencycurrents are supplied to the pole windings 40 by flexible leads 5|extending to terminal bushings 52 mounted in a terminal block 53,provided on one end of the base.y

The bone conduction receiver of Figs. l to 5 is designed for coupling tothe mastoid bone back of the ear of a deafened person and the outersurface of the base 2| has a curved external contact surface 55 grippinga substantial portion of the bone structure of the user so that underthe action of the inertia reaction forces exerted on the casing by thevibratory motion of the floating magnetic structure inside the casing,the base will impart through lits contact surface hearing inducingvibratory forces to a substantial portion of the bone structure engagedby the concave contact surface of the base and thus secure agoodimpedance match between the small vibrating unit and the boneYstructure enabling efficient transmission of hearing inducing vibratoryenergy to the inner ear of the user.

The bone conduction receiver is provided with an inconspicuous head-band55 made from. two

looped spring wires bent to t comfortably over the head of the userwithout making his impairment conspicuous and carrying on its end abracket 56 with arms 51 having pivot pins engaging openings in the sidewalls of the receiver casing for holding the receiver and pressing itsbase 2| against the mastoid bone behind the ear of the user.

To secure an efllcient coupling connection between the receiver base 2|and the bone structure of the user, the lower end of the head-band wireloop 55 is bent to form a bearing sleeve in which is journaled a pivotpin 6| extending between the arms of a link 60 provided with an offsetpivot pin engaged by the center portion of the receiver bracket 56. Thearticulated connection between the head-band 55 and the bracket 56 withthe two pivot pins 6| and 62 permits lateral as well as angular movementof the receiver against the head-band and secures automatic alignment ofthe contact surface of the reeciver base 2| with the bone structureagainst which it is held pressed by the headband. Fig. 4a shows anarticulated link connection between the wire head-band and the receiverbracket, rising a straight link 64 pivotally interconnected by pivot pin6| with the qoffset bearing portion'of the wire loop and by the straightdownward pin 63 with the receiver bracket 56. i

The bone conduction receiver of the invention is designed for use in a.wearable hearingaid device which may be operated by supplying itsactuating winding 40 through flexible cords 64 with sound frequencycurrent oscillations` from a wearable electric amplifying hearing aid,for instance, of the type disclosed in United States Patent No.2,046,738, comprising a transmitter microphone 65 and an amplifier unit66 connected to a small battery 61 by a flexible cord 68 and controlledby a single button control unit 69 combined with the transmitter, allthe parts of which may be hidden in the clothing of the user.

Sound waves imparted to the diaphragm of the transmitting microphonegenerate sound frequency impulses which produce in-the amplifier 66amplified current oscillations which are supplied through the cord 64.to the actuating windings 40 of the bone conduction receiver. Thesecurrent oscillations induce in the small gaps between the pole pieces 36and the armature 23 corresponding vibratory forces which tend to producea vibratory motion between the armature 23 and the floating corestructure 24. Since the floating core structure has a mass ofsubstantial inertia, it resists the vibratory motion and exerts on thearmature inertia reaction forces proportional to the mass of itsfloating core structure and its acceleration, which are, in turn,transmitted through the contact surface of the receiver base 2| to thebone structure of the user for inducing hearing in his inner ear.

In the bone conduction receiver shown in Figs. l to 5, the height of thereceiver casing is held down to a minimum and each part of the spacewithin the tiny receiver casing is efciently utilized for housing thelarge mass of the floating magnetic core structure which combines withinthe small space conilned tol the height of the magnetic bars the corepole pieces with their actuating windings as well as the gap settingmechanism for fixing the dimensions of the vibratory structure requiredto maintain the flxed effective gap spacing of the order of a fractionof a thousandth of an inch essential for producing with the smallreceiver the large mechanical hearing inducing energy that has t beimparted to bonesof the user in order to induce in his inner ear organssatisfactory hearing.

InFigs. 7 to 11 is shown `a modification of the bone conduction receiverof the invention designed to impart hearing-inducing vibrations to thevertebrae of the spinal column of a deafened person and make him hear bybone conduction in the way disclosed in the applications of Hugo Lieber,Serial No. 648,733, filed December 24, 1932, Patent No. 2,077,425,issued April 20, 1937, and Serial No. 21,706, led May 16, 1935, PatentNo. 2,077,426, issued April 20, `1937.

The bone conduction receiver of Figs. 7,to 10 comprises a fiat casingformed of a base10 and a cover 1| enclosinga fiat hollow space withinwhich is mounted a at floating magnetic core structure 12 carried by theends of a resilient diaphragm 13 of a magnetic armature member 14clamped to an anchor plate 15 imbedded in the molded base. `The floatingmagnetic core structure 12, which fills substantially the entire spacewithin the` casing, is formed of two longitudinal permanent magnet bars18, having ends of reduced thickness attached by 'screws 19 to crosspieces 80 of T-shaped `pole core members bent in the Way shown in Fig. 7so that the total height of the floating structure does notsubstantially exceed the height of the permanent magnet bars 18.

As in the bone conduction receiver of Figs. 1 toi5, the pole coremembers 8| are provided with inwardly extending pole piece projections83, and the floating core structure is attached to the ends of thearmature diaphragm 13 by means of screws 84, the diaphragm beingmagnetically in,- sulated from the core members 8| by non-magneticSpacers B5. Set screws 81 `extending through the intermediate portionsof the pole projections 83 and engaging the cross pieces' 80 of the polecore members enable accurate fixing of the dimensions of the vibratorystructure` required to maintain the effective magnetic gap distance `ofthe order" of a fraction of a thousandth of an inch essential foreilicient operation of the receiver. The pole pieces 83 are providedwith energizing coils confined between the magnet bars .18 and suppliedwith sound frequency current through the terminal bushing 89, mounted onthe bushing support extending from the upper end of the base 10.

In order to permit effective coupling of the external contact surface 90of the base 10 to the spinal vertebrae 9| of the bone structure,indicated in dotted line in Fig. 9, the bottom wall and the sidewalls ofthe casing cover 1| are provided with fastening strips 93 formed, forinstance, of metal molded as a unit with the casing cover in the wayshown in Figs. 7 and 9. Each fastening strip is provided with a slot 94to which are attached two lateral straps 95 and one rear strap 96 whichform a suspender-like harness by ngans of which the coupling surface 90.of the vibrator is held 4pressed against the bone structure of thespinal vertebrae 9|. Each of the straps 95 and 95 may be provided withe'nd straps 91 which may be attached to buttons 98 of a belt 99. Thethree straps 95 are provided with buckles |00 similar to those used instandard Suspenders permitting adjustment of the length of-the threestraps 96 so as to secure the desired coupling connection between thebase 10 of the boneconduction receiver and the spinal vertebrae.

The suspender-like harness may be further provided with an additionalcross strap |00 exi column.

w In Figs. 13 to 15 is shown an inertia-reaction bone conductionreceiver of the cantilever type `constructed in accordance with theinvention.

It comprises a flat casing having a base |00 and a detachable cover |0|enclosing a ilat magnetic core structure |02 floatingly carried by anarmature mernber |03 clamped to the base `by screws |04. `The floatingcore structure |03, which fills substantially the entire space withinthe receiver casing, is formed of two longitudinal permanent magnetbars, the ends of which are attached by screws |06 to the upwardlyprojecting overlying cross piece |01 of the `T-shaped doubly bent polecore member |08, the lower end of which forms the armature |03 which isclamped to the receiver base l0 so that the two magnet bars |05 areoatingly carried by the upward armature extension |08 inthe space withinthe casing,

The other ends of the permanent magnetbars |05 are attached by screws||0 to an underlying cross piece of a T-shaped `pole core member ||2having a center portion bent in the way shown in Fig. 13 to form a polepiece ||4 with a pole face lying opposite a pole face portion of thearmature member |03 located in the center of the receiver base |00 whichserves as the coupling wall of the receiver. The central pole piece ||4of the receiver is provided with an actuating coil ||5 which isenergized through flexible leads connected to terminal bushings ||8located in the terminal block extending from one end of the base.

Accurate and simple manufa ture of such bone f conduction receivers withthe "ute fixed effective magnetic gap length between the pole faces ofthe vibratory structure is made possible by a set screw |1 extendingthrough the intermediate portion of the T-shaped pole core ||2 andengaging with its tip the mid-portion of the cross piece so that byturning the set screw ||1 the pole piece ||4 is withdrawn from itsposition in contact with the armature pole face and the effectivemagnetic gap is xed at its optimum minimum length essential for theefllcient operation of the small receiver.

In the cantilever-type inertia reaction receiver shown in Figs. 13 tol5, the pole piece ||l` is located above the center of the base and themagnetic forces are developed in the center of the receiver unit. As aresult the inertia reaction forces exerted by the oating mass of thevibratory structure on the base will transmit vibratory energy over themajor part of the base area and the receiver base may be provided with alarge concave coupling surface which is pressed against the bonestructure by the pins of a head band bracket which engage the holes |9`of the receiver tremely small height and over-al1 size, are able tohouse a large floating magnetic core structure operating at greateiciency with a xed minute effective gap length of a fraction of athousandth of an inch secured by utilizing the elements o f the floatingcore structure as a positive gap fixing mechanism will suggest to thoseskilled in the art many other embodiments of the invention. It isaccordingly desired that the appended claims be given a broadconstruction commensurate with the scope of the invention.

1. In a wearable bone conduction hearing-aid receiver for a deafenedperson, a receiver casing, a magnetic vibratory core structure ofsubstantial mass enclosed in said casing comprising two spaced permanentmagnet bars and two core cross pieces joining the opposite ends of saidbars into va rigid flat core of substantial mass, one of said crosspieces constituting a part of a pole piece extending from said crosspiece and confined in the space between said bars, and a driven coremember united with a wall of said casing floatingly carrying the fiatcore within said casing. said fiat core filling substantially the entirespace within said casing and constituting with said driven core memberan electromagnetically actuated vibratory structure of fixed dimensionsforming a low reluctance magnetic flux path including a gap.

2. In a wearable bone conduction hearing-aid receiver for a deafenedperson, a receiver casing, a magnetic vibratory core structure ofsubstantial `rnass enclosed in said casing comprising two spacedpermanent magnet bars and two core cross pieces joining the oppositeends of said bars into a rigid at core of substantial mass, each of saidcross pieces constituting a part of a pole piece extending from saidcross piece and confined in the space between said bars, and a drivencore member united with a wall of said casing floatingly carrying thefiat core within said casing, said flat core lllng substantially theentire space within said casing and constituting with said driven coremember an electromagnetically 'actuated vibratory structure of fixeddimensions forming a low reluctance magnetic flux path including a gap.

3. In a wearable bone conduction hearing-aid receiver for a deafenedperson, a receiver casing, a magnetic vibratory core structure ofsubstantial mass enclosed in said casing comprising two spaced permanentmagnet bars and two core cross pieces joining the opposite endsof saidbars into a rigid fiat core of substantial mass,one of said cross piecesconstituting a part of a' pole piece Within said casing driven coremember an electromagnetically actuated vibratory structure of fixeddimensions forming a low reluctance magnetic flux path including a gapof the order of a fraction of a thou' sandth of an inch between saidpole piece and said driven core member, and set screw means extendpolepiece and engaging another spaced portion of said pole piece for xingthe structural relation of the oating flat core relatively to the drivencore member and maintaining between said pole piece and said driven coremember an eiective magnetic gap.

4. In a wearable bone conduction hearing-aid receiver for a deafenedperson, a receiver casing,

spaced permanent magnet bars and two core cross pieces joining theopposite ends of said bars into a rigid fiat core of substantial mass,each of said cross pieces constituting a part of a pole piece extendingfrom said cross piece and confined in the space between said bars, and adriven ing, said nat core filling substantially the entire space withinsaid casing and constituting with said driven core member anelectromagnetically actuated vibratory structure of xed dimensionsforming a 10W reductance magnetic ux path including a gap of the order`of a fraction of a thousandth of an inch between said pole piece andsaid driven core member, and set screw means extending through each ofsaid pole pieces and engaging another spaced portion of said pole piecesfor fixing the structural relation of the oating at core relatively tothe driven core member and maintaining between said pole piece and saiddriven core member an eiective magnetic gap. EMMANUEL CHRIST NICHOLIDES.

